/usr/share/doc/python-pyparsing-doc/examples/macroExpander.py is in python-pyparsing-doc 2.2.0+dfsg1-2.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 | # macroExpander.py
#
# Example pyparsing program for performing macro expansion, similar to
# the C pre-processor. This program is not as fully-featured, simply
# processing macros of the form:
# #def xxx yyyyy
# and replacing xxx with yyyyy in the rest of the input string. Macros
# can also be composed using other macros, such as
# #def zzz xxx+1
# Since xxx was previously defined as yyyyy, then zzz will be replaced
# with yyyyy+1.
#
# Copyright 2007 by Paul McGuire
#
from pyparsing import *
# define the structure of a macro definition (the empty term is used
# to advance to the next non-whitespace character)
identifier = Word(alphas+"_",alphanums+"_")
macroDef = "#def" + identifier("macro") + empty + restOfLine("value")
# define a placeholder for defined macros - initially nothing
macroExpr = Forward()
macroExpr << NoMatch()
# global dictionary for macro definitions
macros = {}
# parse action for macro definitions
def processMacroDefn(s,l,t):
macroVal = macroExpander.transformString(t.value)
macros[t.macro] = macroVal
macroExpr << MatchFirst(map(Keyword, macros.keys()))
return "#def " + t.macro + " " + macroVal
# parse action to replace macro references with their respective definition
def processMacroRef(s,l,t):
return macros[t[0]]
# attach parse actions to expressions
macroExpr.setParseAction(processMacroRef)
macroDef.setParseAction(processMacroDefn)
# define pattern for scanning through the input string
macroExpander = macroExpr | macroDef
# test macro substitution using transformString
testString = """
#def A 100
#def ALEN A+1
char Astring[ALEN];
char AA[A];
typedef char[ALEN] Acharbuf;
"""
print(macroExpander.transformString(testString))
print(macros)
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